This invention relates to fluid-powered, reciprocating motors.
Fluid-powered, reciprocating motors are used for a variety of applications including power tools, liquid pumps and the like. In one type of such motors, a piston mounted for reciprocative movement inside a cylinder is driven in one direction by a spring acting on one side of the piston and is driven in the opposite direction by a pressurized liquid or gas acting on the other side of the piston. Flow of the pressurized fluid from the cylinder is controlled by a valve which is opened and closed in response to movement of the piston. Prior constructions for this type fluid-powered pumps are exemplified in U.S. Pat. Nos. 1,780,817, 2,630,181, 2,789,510, and 3,230,839.
Such motors require a relatively large piston return spring which makes it difficult to control piston movement so that the speed and/or power of both strokes is substantially the same.
U.S. Pat. No. 3,500,735 discloses a pneumatic motor which employs pressurized air to power a piston in both directions. However, the motor is designed to operate only on a compressible gas, such as air. Also, the motor requires separate air supplies, one regulated and the other non-regulated.